Garden Talk: September 9, 2010

From NGA Editors

Selecting the Best Roses

Part of the mission of the American Rose Society (ARS) is the evaluation of newly-released roses. After three years of assessment, each rose is assigned a rating that is included in their annually published Handbook for Selecting Roses.

But recognizing that, as a rose is grown more widely over the years, its initial rating may become outdated, the ARS also began reviewing the ratings of established varieties periodically. They have just released the results of their first Quinquennial (Five Year) Survey, done in 2010, in which approximately 500 rose growers evaluated the ratings of all roses introduced before 2000.

As in past surveys, some of the highest rated roses showed a slight decline, but overall the rating of as many roses increased as declined. Ratings range from 9.3-10 for "One of the best roses ever" and 8.8-9.2 for "An outstanding rose in the top 1%" to 0.0-6.0 for "Not recommended" for over 3000 roses now in commerce in North America.

And what roses came out on top? The Noisette rose 'Reve d'Or', with medium yellow double blooms, maintained its top billing, with a score of 9.2, although it now shares the spotlight with two species roses, White Rugosa Rose (Rosa rugosa alba), with single, white blossoms and Lady Banks' Rose (Rosa banksiae banksiae) (pictured), with double, white flowers, both of which also received a 9.2 rating. Interestingly, in spite of all the new rose varieties released each year, all three of these top-rated roses are heirloom varieties. Reve d'Or dates to 1869, Lady Banks' to 1807 and the white Rugosa to 1784.

The Handbook for Selecting Roses is available from the American Rose Society for $5. In addition to an alphabetical listing of roses with their ratings, it contains useful lists of top rated roses by category, as well as award winners.

For more information on the American Rose Society or to purchase the Handbook for Selecting Roses, go to: American Rose Society.

Avoiding the Mummy's Curse

Blueberries are a popular fruit for home gardeners. They are generally easy to grow and the berries are delicious and highly nutritious. But sometimes the mature berries shrivel up, turning gray and hard. Blossoms turn brown and dry up, immature berries may fall before they ripen and eventually the tips of branches may wilt and die.

The cause of all these symptoms is a fungal disease called mummy berry. It occurs sporadically, usually after a cool, wet spring. It's a difficult disease to control because once you see the mummified berries, it's too late to do anything other than clean up and destroy all the infected berries to minimize the amount of fungus that overwinters.

So it's helpful to know which varieties of blueberries show the most resistance to this disease. Researchers at the USDA Agricultural Research Service recently estimated the relative resistance of different blueberry varieties by quantifying the average annual percentage of blighted shoots and mummified berries on a large number of cultivars.

Among the ones with the fewest mummified berries (less than 3%) were 'Brunswick', 'Chignecto', 'Fundy', 'Putte' and 'Zuckertraube' low bush blueberries, 'Chippewa', 'North Country,' 'Northsky' and 'St. Cloud' half highs (cross between low and high bush), and 'Pearl River', a cross between a southern highbush and rabbiteye blueberry. The highbush cultivars that rated best (10.3% or less mummified berries) were 'Bluegold', 'Bluejay', 'Brigitta Blue', 'Patriot', 'Reka', 'Reveille' and 'Weymouth'. The varieties with the lowest percentage of blighted shoots did not always track with the ones with the fewest mummified berries, but among the highbush cultivars, the authors noted that 'Bluejay' was reliably resistant to both types of damage.

Don't Baby Your Basil

Most gardeners know that many perennial herbs such as rosemary, thyme and sage are most flavorful when grown in lean soil without a lot of fertility. But more fertile soil has often been recommended for annual herbs such as basil.

In some interesting new research done at Southwestern University, nitrogen fertilization was found to have a significant effect on the levels of phenolic compounds in both 'Genovese' and 'Dark Opal' basil. These are the compounds that give this herb its healthful antioxidant properties. In the case of both basil cultivars, the level of phenolic compounds was highest when nutrient availability was lowest. So, although higher rates of fertilization may result in lusher growth, for the highest antioxidant activity and nutritional value, go easy when adding nitrogen fertilizer to your basil crop.

Leaf Collection Made Easy

Soon gardeners in many parts of the country will begin that traditional fall chore- raking up leaves. While a few leaves can just be mown over to return organic matter to the soil, large amounts need to be removed from lawns to keep the grass from suffocating. But don't bag your leaves and haul them to the landfill. Autumn leaves are great as the basis for a compost pile and can be chopped to make mulch for garden beds.

While raking in the cool, crisp fall weather is enjoyable, it is still work and tools to help you get the leaves from lawn to compost bin make the process less of a chore. Save your back from lots of bending and scooping with Clean Air Gardening's Rollable Giant Leaf Collection Bag. Holding up to 9 cubic feet of material, you can rake leaves and garden debris directly into the tear-resistant bag, then, with its pull handle and two heavy duty poly wheels, easily maneuver it to the compost bin. And when you're done, the Collection Bag folds for easy storage.

Make your life even easier by clipping the back-saving Stout's BackSaver Grip to the handle of your rake. It works by increasing the leverage and efficiency of your body and the tool as you work, reducing back and shoulder strain with its ergonomic design.

For more information on both these products and other leaf collection tools, go to: : Clean Air Gardening.